Many are seeing Ascochyta leaf blight and wondering what it is

What are those irregular brown patches on my lawn this summer? This is a fungus called Ascochyta leaf blight. It is primarily a leaf fungus that shows up in perennial ryegrass, tall fescue and Kentucky blue grass. If the problem were grubs, tugging on the grass blades would release the crown from the soil.

This leaf blight is preceded by cool, rainy conditions that transition into hot, dry periods. This can occur overnight. The tips of the grass blade are pinched and bleached about a third of the way down the rest of the grass blade. There is minute yellow to dark brown, flask-shaped fungal fruiting bodies called pycnidia in diseased leaf tissue. These can be seen with a hand lens.

How do you manage Ascochyta leaf blight? Have your lawn aerated yearly making sure that the turf is properly aerated. This means that the plugs must be two inches apart and go deep enough while aerating vertically, horizontally and diagonally across the turf. If it is not done this way, then aeration will be less effective.

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